TY - JOUR T1 - Subtype-Specific Intracellular Trafficking of α<sub>2</sub>-Adrenergic Receptors JF - Molecular Pharmacology JO - Mol Pharmacol SP - 711 LP - 720 DO - 10.1124/mol.51.5.711 VL - 51 IS - 5 AU - David A. Daunt AU - Carl Hurt AU - Lutz Hein AU - Jaana Kallio AU - Felix Feng AU - Brian K. Kobilka Y1 - 1997/05/01 UR - http://molpharm.aspetjournals.org/content/51/5/711.abstract N2 - The three α2-adrenergic receptor subtypes (α2a, α2b, and α2c) are highly homologous G protein-coupled receptors. These receptors all couple to pertussis toxin-sensitive G proteins and have relatively similar pharmacological properties. To further explore functional differences between these receptors, we used immunocytochemical techniques to compare the ability of the three α2-receptor subtypes to undergo agonist-mediated internalization. The α2a-receptor does not internalize after agonist treatment. In contrast, we observed that the α2b-receptor is able to undergo agonist-induced internalization and seems to follow the same endosomal pathway used by the β2-adrenergic receptor. Attempts to examine internalization of the α2c-receptor were complicated by the fact that the majority of the α2c-receptor resides in the endoplasmic reticulum and cis/medial Golgi and there is relatively little cell surface localization. Nevertheless, we were able to detect some internalization of the α2c-receptor after prolonged agonist treatment. However, we observed no significant movement of α2c-receptor from the intracellular pool to the plasma membrane during a 4-hr treatment of cells with cycloheximide, suggesting that these cells are unable to process α2c-receptors in the same way they process the α2a or α2b subtypes. ER -